Catching wildfowl by artificial light ROY H. DENNIS

At Fair Isle Bird Observatory we use an Tilley radiator heater, which has a heating assortment of methods for catching birds mantle mounted on a vaporizer and a dish to ring. The majority of our catch each year reflector. The base of the heater is a are either passerines trapped in permanent pressurised tank for holding paraffin; a Heligoland traps, small wire traps and pump is fitted in the side of the tank for mist-nets, or Fulmars, Shags, auks and pumping the paraffin up the vaporizer and gulls, ringed on the cliffs. Since 1959 we into the heating mande. We had the have been catching a variety of species by reflector silvered and replaced the heating the use of artificial light at night. We have mantle with a 500 candle power lighting been particularly interested in those species mantle shielded by a glass dome for outside which do not usually enter our normal work. Another lamp we converted has a traps, including wildfowl, waders and 300 c.p. mantle and we find this nearly as wintering gulls. We have so far caught and efficient and easier to keep alight. ringed by the use of artificial light about This equipment gives a very strong wide 630 birds of 51 species. In 1965, we caught beam. A powerful torch with a narrow 166 birds of 28 species by this method beam is not as efficient, because one has alone. to spend so much time sweeping with the Fair Isle is generally speaking a poor torch beam to find a bird, whereas the place for wildfowl. Thirty species of wild­ Tilley lamp gives off a beam of, say, 150° fowl have been recorded on the island, but arc and illuminates all the birds in front of all, except the Eider which breeds, are the operator. Also, on Fair Isle, we find it usually recorded in small numbers on cheaper and handier to run a lamp on migration. The latest addition to the list paraffin, rather than buying batteries for a was a pair of Harlequin Ducks, which large torch, especially as the batteries are stayed in one of the geos from n th only of use for dazzling when they are new; January to 2nd February, 1965. Most of once they are slightly run down they lose the wildfowl recorded are on diurnal most of their effectiveness for dazzling. passage past Fair Isle and after flying over The other piece of essential equipment the island or circling a few times they is a good hand-net: really one needs continue their migrations. In bad weather, several hand-nets suitable for different some of them stop on the island to await weather conditions and species. We make better conditions and it is at these times our nets from a length of stout fencing that they roost overnight on the island wire, which we shape into a circle, from and we have a chance to dazzle-net them. one-and-a-half to three feet diameter. A The migrant sea-ducks stay in the rocky net is fixed on to the wire; for smaller birds bays and are generally out of our range, but we use a small mesh and do not have much the rest of the ducks, geese and swans ‘bag’ on the net and for larger birds we usually roost on the island. Invariably, use a larger mesh and have more ‘bag’. If they roost in a different area from that the mesh is too big, the birds tend to get where they spend the day and most of tangled and time is wasted in extracting them are found at night on small lochs or them. The ends of the wire are twisted bums. Mallard and Teal, which have together and bound tightly to the end of a become ‘semi-resident5 on the island, bamboo cane or long stick. For all purposes forage at night in the burns and marshy we prefer the longest and lightest pole and areas. the largest diameter of net. Our best hand- One difficulty with the dazzle-netting net has a 12 ft. bamboo handle, but often technique is that the weather conditions the wind is too strong and the larger hand- must be suitable otherwise one will have nets become unwieldy. It is important that little success. The ideal night is one with the handle is firm and does not whip in a no moon, a howling gale and lashing rain; wind and that the wire frame is tightly if one is brave, or daft, enough to venture bound to the handle so that the net will not out with an artificial light and a net, there swing in the wind or rattle against the is a very good chance of catching wildfowl handle when in use. We use binding wire and waders. and string to join the net to the handle and finish it off with adhesive tape. Equipment When dazzle-netting we always carry a The most important item of equipment is a small rucsac containing bird-bags and powerful lamp. We now use, after trying sacks for holding the catch, an electric a variety of electric torches, a converted torch, note book for recording retraps and Tilley lamp. Originally, this lamp was a matches for re-lighting the Tilley if it

98 THE WILDFOWL TRUST blows out. We wear long rubber boots so man can then extract the bird in the shadow. that we can wade into wet areas. We find The bird is put in a bag and carried by the the oilskins make too much noise as we lamp-man. It is generally easier to catch a walk and scare the birds, so we wear single bird than one from a flock. Approach anoraks. can be made from any direction, but we find into the wind or across it more successful. M ethods Geese and waders tend to walk steadily On Fair Isle the summer months are too away from the light and then stop and light and the first nights suitable for dazzle- run towards it; both persons should walk netting are in August. The best team for quickly and quietly after the birds until dazzle-netting on Fair Isle consists of two within catching distance. Diving-ducks in people; the lamp-man who carries the shallow pools tend to become dazzled lamp sind the net-man who walks directly easily and dive as soon as they are netted or behind, holding the net. It takes practice become worried. The net should be lowered to become a good team, because the net- quickly over them and pulled towards the man must keep directly behind the leader net-man so that the bird is caught in a bag and not switch on a torch to find his way of netting, sealed by the wire rim of the over rough ground. Our routine on a net; scooping up by a ‘shrimping5 motion suitable night is to make a circuit of the does not seem to work. island, visiting various small lochs and We have on two occasions dazzle-netted marshes and walking along streams. Nearly birds on the sea from a boat. Both birds all wildfowl and waders prefer to roost (a Long-tailed Duck and a Little Grebe) overnight on or beside water and the were easily dazzled, once we had found choice of roosting area is affected by wind them. We caught them by dropping the direction and strength. On suitable nights net over them and pulling them into the we walk up the Gilsetter burn to Sukka boat, rather than trying to scoop them up, Mire and the Mire of Vatnagard, which when the net would be visible to them as are favoured roosting places because they it entered the water between them and the are marshy areas dotted with small pools, lamp. Dazzle-netting from a boat has a in an isolated part of the island. great potential, but it requires a great deal The leader carries the lamp, in front of of local knowledge of boats, tides and him, shining it on to pools and streams; rocks. Wildfowl are probably easier to most birds show up as a pale dot in the dazzle-net on open water than they are on beam. The light is shone at the bird and land, where they are always wary of both persons approach as silently as ground predators. possible. Usually the bird either flies away as soon as the light is shone on to it or else When dazzle-netting Whooper Swans it it is dazzled and stays on the pool. No is better to use a swan-hook rather than a net to catch them. They are quite easy to talking should be necessary and it takes practice for the net-man to decide which dazzle but rather a job trying to control in bird is being dazzled without actually the dark. If one flies off, it is well worth being told by the leader. Ducks, once they calling like a swan; they usually answer are dazzled, tend to swim slowly away or and land nearby. round in circles but great care should be We usually take all our captures back to taken not to scare them by rushing after the Bird Observatory for examination and them. Making a splash as you step into ringing. If it is a wet or windy night we water is the quickest way to lose a duck. generally roost them overnight at the Bird Care must be taken to walk quietly through Observatory in a dry tea chest and release water, keeping the light shining on the them at dawn, rather than releasing them bird. On really dark nights, some wildfowl into a gale at night. If a bird is ringed will actually swim towards the light. If the immediately after capture, rather than bird is swimming quietly in front of the being taken back to a base for ringing, it lamp-man, the net should be lowered to must be held away from the light for head height, so that the distance can be several minutes and allowed to become judged, and then brought down quickly accustomed to the darkness before being over the bird. The net-man should not released. move out of the shadow before the net is During 1965 we dazzle-netted and ringed over the bird. There are now two courses of the following wildfowl at Fair Isle; one action. If it is a solitary bird, the net-man Mallard, two Tufted Ducks, one Long­ runs to the net as qu ickly as possible and tailed Duck, one Greylag Goose, one extracts the bird in the light; but if it is Pink-footed Goose, one Barnacle Goose and one bird from a flock, the light-man should three Whooper Swans. In previous years continue to shine the light on the rest of we dazzle-netted and ringed two MaUard, the flock and walk past the net, the net- two Teal, three Wigeon, one Tufted Duck,

CATCHING WILDFOWL 99 three Eiders, two Greylag Geese and four include Heron (2), Ringed Plover (62), Whooper Swans. Little Stint (3), American Pectoral Sand­ Dazzle-netting is an extremely exciting piper (1), Great Black-backed Gull (i i i ), method of catching birds for ringing, even Glaucous Gull (5), and Snow Bunting (5). though it is carried out in very uncom­ Finally, it should be pointed out that all fortable, and sometimes hazardous, weather qualified ringers require a licence to use conditions. Part of the thrill is that you artificial light at night, under paragraph (e) never know what species your lamp beam of sub-Section (1) of Section 10 of the will pick up next. Unusual species we have Protection of Birds Act, 1954. caught and ringed at Fair Isle at night

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